Method and apparatus for the continuous production of paper strips



Feb. 13, 1945. P. DUNSHEATH, 2,369,221

METHOD AND APPARATUS FOR THE CONTINUOUS PRODUCTION OF PAPER STRIPS FiledJune 19, 1942 5 Sheets-Sheet 1 PERCY DUNSHEATH Feb. 13, 1945. P.DUNSHEATH METHOD AND APPARATUS FOR THE CONTINUOUS PRODUCTION OF PAPERSTRIPS Flled June 19, 1942 5 Sheets-Sheet 2 Ll PERCY nuusumni/m z/vraearm M- P. DUNSHEATH METHOD AND APPARATUS FOR THE CONTINUOUS Feb. 13,1945.

PRODUCTION OF PAPER STRIPS 5 Sheets-Sheet 5 Filed June 19, 1942 F/GJO W?2 r/ Win fiu/ WM fl/2 uvvmrm PERCY DUNSHL'ATH ATTO/WVEKS' Fell 1945- P.DUNSHEATH 2,359,221

METHOD AND APPARATUS FOR THE CONTINUOUS PRODUCTION OF PAPER STRIPS FiledJune 19, 1942 5 Sheets-Sheet 4 E) modm ATTORNEYS Feb. 13, 1945. P.DUNSHEATH 2,359,221

METHOD AND APPARATUS FOR THE CONTINUOUS PRODUCTION OF PAPER STRIPS FiledJune 19, 1942 5 Sheets-Sheet 5 PERCY Du NSH EATH B) MMAM Patented Feb.13, 1945 METHOD AND APPARATUS FOR THE CON- TINUOUS PRODUCTION OFPAPER/STRIPS Percy Dunsheath, Abinger, England, assignor to W. T.Henleys Telegraph Works Company Limited, Westcott, Dorking, England, acompany of Great Britain Application J une 19, 1942, Serial No. 447,6477 In Great Britain August 23, 1941 15 Claims. (01. 164-455) Thisinvention relates to improved methods and machines forthe continuousproduction of paper strips. The strips are produced by tearing a. sheetof paper and have edges which are thinned downor taper ofi in thicknessand are irregular and are formed of projecting fibres. Such strips areparticularly suitable for use as the dielectric of an electric cable orcable joint.

Several methods and machines have been devisedbyme for the production ofthe paper strips with edges as described above. In these methods theproduction of a line of weakening of the paper generally willimmediately precede the tearing; they may, in some cases, appear to be asingle operation. In one of the methods the line of weakness is producedby scoring and then the paper is torn so as to beseparated in the regionof this line. By scorin is intended to indicate either a cutting throughpart of the thickness of the paper, or the overstraining of the fibrousstructure of the paper along a line by the sharp edge of a knife.

All the methods of preparing the required edge may include themoistening of the paper to a small extent with water shortly before thetearing takes place. This has the effect of loosening theinterengagement of the fibres so that they slide apart more readily whenbeing torn, pro ducing a more open edge.

The invention will be described further with the aid of the accompanyingdrawings.

Figures 1. and 2 are a side elevation and plan respectively of one formof machine for scouring and tearing a sheet of paper in the manner shownin Figures 3-5.

Figure 3 represents, on a much enlarged scale, one edge of a portion ofsheet of paper after'it has been scored by the machine shown in Figures1 and 2. v

. Figure 4 represents the sheet of paper of Fig ure 3 after tearing intostrips has been effected, and

Figure 5 is a plan view of the paper strip shown in Figure 3.

Figures 6 and 7 are a side elevation and plan,

respectively of an alternative form of machine for scoring and tearinga, sheet of paper in-the manner shown in Figure8. Fig. 8 is across-sec,- tion on the line VIII-VIII of Figure 6.

mFigure 9 is a longitudinal section joint.

Figure 10 is a similar view of a short length cable, and

, of a cable 4 a-few layers of the paper dielectric of the-cable Figure11 is a much enlarged view representing shownin Figure 10. v a i Figure12 is a plan view of a further alterna; tive form of machine.

Figure 13 is an end elevation, looking in the direction-of the arrowshown in Figure 12.

. Figure 14 is a side elevation. :Figure "15 shows in side elevation anumber of the tearing devices constructed in accordance with Figure 12,and

Figure 16 is a view in plan showing the manner in which the strips ofpaper are-caused to diverge when several tearing devices arranged as inFigure 15 are used.

In each of the figures the machines are shown diagrammatically.

Referring first of all to Figure 3, a sheet of paper I is provided oneach side of the-sheet with a series of cuts 2 which extendapproximatelyhalf way through the thickness of the sheet. The cuts oneach side of the sheet are spaced equidistantly but the two sets of cutsare staggered in relation to each other and are so arranged thatadjacent cuts on opposite sides of the sheetare disposed a shortdistance apart (say A; of an inch). The two sets of cuts form parallellines as will be seen from Figure 5.

The two sets of cuts are produced by the 00- number of disc knives 3mounted on shafts 5 as depthv being approximately equal to half thetotal thickness of the paper, as the sheet passes through-the machine.After the cuts have been made on both sides of the sheet I, the latterpasses between a pair of cylindrical rollers] and just in front of thesethe sheet is torn into a number of separate strips 8 by passing on to aseries of rollers 9 having their axes lying on thearc of a circle, thecentre of which is approximately at the point of tearing which is justin front of the nip of the rollers l. The are of the circle lies in avertical plane. In plan the rollers 9 overlap each other slightly aswill be seen from Figure 2, the separate strips being taken oil to theroller 9 in a progressively upward or downward direction from one edgeof the sheet or the other.

The tearing of the sheet I into separate strips 3 takes place in theregion of a pair of adjacent cuts on opposite sides of the sheet and thegeneral effect of the tearing is represented by Figure 4. It will beseen from that figure that between adjacent cuts on opposite sides ofthe sheet the sheet is torn into two portions III, II havingapproximately half the thickness of the original sheet, each individualstrip thus having a central portion of a thickness equal to that of theoriginal sheet and aportion at each end having a thickness approximatingto half that of the original sheet. The thinner portions I formcontinuations of the upper parts of the strips and the other portions IIcontinuations of the lower parts of the strips. The sheet I is drawn offfrom a rotatably mounted paper roll 40 by the rollers 9 being driven inthe direction of the arrows shown in Figure 1.

Figure 4 is intended only to show the general effect of the tearingaction and although the portions In and II have been shown in thatfigure as being symmetrical and with straight edges and sharp corners,it will be understood that in practice the surfaces at these places willbe rough and irregular, the tearing action causing the fibres of thepaper to be drawn out and to project from those surfaces. Furthermorethe tapering may be more gradual than that shown in the figure.

The machine just described is particularly suitable for use with sheetsof paper made in two plies, in which case there is a substantialseparation of the two plies combined with a dragging out of fibres. Theaction takes place more effectively if the region to be torn ismoistened before tearing.

The outer edges of the sheet, of course, will not be torn so that theindividual strips having those edges will be discarded. The machineshown in Figures 1 and 2 provides for the production of five stripssimultaneously, each strip having two torn edges.

In the machine shown in Figures 6-8 inclusive, the sheet I of paper iscut or scored in parallel lines and on one side of the sheet only andimmediately after this has been eifected the sheet is torn into separatestrips. The machine as shown comprises an upper cylinder I4 having anappropriate number of axially spaced circumferential grooves IS in itsperiphery, the grooves being of rectangular cross-section. The machinealso has a lower cylinder I5 provided on its surface with a number ofcircumferential projections I8 having sharp edges I! which stand up fromthe surface of that cylinder and enter the grooves I6 in the uppercylinder I4. In the machine as shown there are five sharp edges and fivegrooves and the cross-section of each circumferential projection, asseen in Figure 8 is triangular.

As will be seen from Figure 8, the width of the projection I8 at itsbase is substantially equal to that of the groove I6 and the totallength of two sides of the projection is substantially greater than thewidth of the groove. As the sheet I approaches the machine it is engagedon its underside by the edges I! of the projections I8 and when thesheet enters the nip of the two cylinders I4 and I5, the sheet is heldon the two opposite sides of a groove and the portion of the paper lyingbetween those parts and over a projection I3 is scored or weakened bythe sharp edge I! and that portion of the paper is then immediatelyafterwards torn in the neighbourhood of the weakened part by beingstretched over the projection I8. In Figure 8 the adjacent torn edgesare represented by the reference numerals IS. The tearing of the sheetin this manner produces two separate strips, the adjacent edges of whichare thinned down and are rough due to the fibres being pulled out by thestretching process. The separate strips are wound on to two sets ofrolls 9, one set being placed above the other.

Instead of using a continuous sharp edge such as that shown at II, adiscontinuous one may be used, the edge being serrated and formed of anumber of fine teeth.

In the machines already described the torn paper strips are caused todiverge in the vertical direction. In the machine shown in Figures 1216,the strips ar caused to diverge laterally and lie in a horizontal plane.

Referring first of all to Figures 12-14, there is shown a machine whichto a certain extent resembles that shown in Figure 6 in so far as bothmachines make use of a rotatable lower cylinder I5 having on its surfacea circumferential projection I8 provided with a sharp edge II.Co-operating with the lower cylinder I5 are two rotatable uppercylinders 31 having friction surfaces, for example, they may each becovered with a layer of rubber. The two upper cylinders, as will be seenfrom Figure 12, do not lie parallel with the path of travel of the sheetI but have their axes disposed obliquely to that path, the adjacentfaces of the cylinders diverging outwards by a small angle in thedirection in which the sheet moves. The cylinders 31 are also soarranged that the points of contact between those cylinders and thelower cylinder I5 lie in the central vertical planes of the uppercylinders. Although reference has been made to points of contact therewill be in fact a certain amount of compression of the rubber. on thecylinders 31 so that contact between the upper and lower cylinders willtake place over lines or areas rather than at points.

As the sheet I is drawn through the machine it is scored or weakened andis then torn over the edge II of the lower cylinder I5 and the eparatestrips 8 so formed are drawn apart or caused to diverge laterally by theupper cylinders 31, the strips being subsequently wound up on therollers 9. The rollers 31 or 9 may be driven rollers.

In Figur 15 there are shown three lower cylinders I5 each having a sharpedge I'I, each cylinder co-operating with a pair of upper cylinders 31.In this arrangement, the process of scoring or weakening, followed bytearing, is repeated. thus each strip 8 when formed is furthersubdivided into two narrower strips. The two strips of a pair are causedto diverge in the manner already described and as shown in Figure 16 andall the strips lie in the same horizontal plane.

A already indicated above, in each case, the paper may be moistened inthe region at which the paper is to be torn, before actual tearing takesplace. It will also be necessary or desirable to provide the supply roll40 with some convenient form of adjustable frictional device to preventoverrunning of that roll and to control the tenslon in the paper.

game

Ithas already been indicated above that paper having edges produced bythe present invention may be'used as the wrapped dielectric at a cablejoint as well a for the dielectric of acable. In V Figure 9 there isshown a joint made between two lengths of cable, each having a singleconductor. The joint-is enclosed in a metal ferrule 3| and theconductors, ferrule and adjacent paper dielectric of the two cablelengths are provided with an insulating wrapping 32 of paper. The latterconsists of strips of paper applied helically and having edges preparedby any of the methods described above. In this figure no attempt hasbeen made to illustrate the individual strips forming the wrapping. v

In Figure 10 thereis shown a cable having a single central conductor '33enclosed in a paper wrapped dielectric 34 consisting of several layersapplied helically and each consisting of a strip of paper having itsedges prepared by the machine shown in Figure 1 and 2 and Figure 11 is amuch enlarged view representing a few layers of the cable dielectric.The latter figure shows very approximately the kind of effect producedat the edges by the tearing action showing a thinning down of the papercaused by the dragging out or loosening of the fibres. The figure alsoshows the filling up to a large extent of the gaps which would normallyexist between adjacent convolutions. The dielectric 34 is enclosed in alead sheath 35 in the usual manner.

For th insulation of an electric cable or cable joint consisting ofhelically applied strips of paper, strips of considerable length arerequired. The machines described above provide simple means for thecontinuous production of paper strips of considerable lengthhavingthinned down and irregular edges formed of projecting fibres, thusfacilitating the manufacture of cables and joints in which the helicalspaces normally oc curring between the adjacent turns of astrip arelargely occupied by th projecting fibres at the edges of the strip.

What I claim as my invention is:

1. A machine for the continuous production of paper strips havingthinned down irregular edges formed of projecting fibres, the saidmachine comprising a supply device for a rolled sheet of paper and ascoring device comprising at least two pairs of cooperating cylindersfor producing on opposite sides of the sheet closely spaced par allellines of weakening, each pair of cooperating cylinders consisting of arotatable cylinder having a smooth surface and a rotatable cylinderhaving a sharp edge projecting from its periphery, and means fordeflecting at least some of the strips out of the plane of the path ortravel of the sheet through the machine.

2. A machine for the continuous production of paper strips havingthinned down irregular edges formed of projecting fibres, the saidmachine including a supply device for a rolled sheet of paper and ascoring and tearing device comprising a pair of cooperating rotatablecylinders one having a circumferential groove and the other acircumferential projection with a sharp edge entering the groove, thetwo cylinders being so disposed as to weaken the sheet and then tear,

it into strips by stretching the sheet over the projection.

3. A machine for the continuous production of paper strips havingthinned down irregular edges formed of projecting fibres, the saidmachine comprising a pair of cooperating rotatable cylinders one havinga groove in its periphery and the other an 'annular' projection with asharp edge entering the groove and of substantially triangular shape incross-section, the dimensions of the projection incross-section beingsuch that the total length of its two sides is substantially greaterthan its width. v

4. A method of manufacturing paper strip having thinned down irregularedges with projecting fibres by producing a line of weakening in a sheetof paper and then immediately stretching the sheet across the line ofweakening to tear it into strip having thinned down irregular edgesformed of projecting fibres.

5. A machine for the continuous production of paper strips havingthinned down irregular edges formed of projecting fibres, the saidmachine comprising a supply device for a rolled sheet of paper andincluding a scoring and tearing device comprising a rotatable cylinderhaving a circumferential projection with a sharp edge and a pair ofcooperating rotatable cylinders for gripping the sheet of paper onopposite sides of the circumferential projection.

6. A machine for the continuous production of paper strips havingthinned down irregular edges formed of projecting fibres, the saidmachine comprising a supply device for a rolled sheet of paper andincluding a scoring and tearing device comprising a pair of axiallyspaced rotatable cylinders, a third rotatable cylinder cooperating withthe pair of cylinders and having an annular projection with a sharp edgeprojecting into the space between the pair of cylinders, the latterbeing so disposed in relation'to the third cylinder as to grip a sheetof paper on opposite sides of the projection and to tear it into stripsand to lead off the strips in laterally diverging directions.

'7. A machine for the continuous production of paper strips havingthinned down irregular edges with projecting fibres, the said machinecomprising a supply device for a rolled sheet of paper, means forproducing laterally, closely spaced parallel lines of weakening uponopposite sides of the paper sheet and means for tearing the tending fromone line to the other.

8. A method of manufacturing paper strips having thinned down irregularedges with projecting fibres by producing laterally, closely spacedparallel lines of weakening upon opposite sides of the paper sheet andtearing the sheet along the lines, the tear extending from one line tothe other.

9. A machine for the continuous production of paper strips havingthinned down irregular edges with projecting fibres, the said machinecomprising a supply device for a rolled sheet of paper and means forscoring laterally, closely spaced parallel lines upon opposite sides ofthe paper sheet and means for tearing the sheet along the lines, thetear extending from one line to the other.

10. A method of manufacturing paper strips having thinned down irregularedges with pro- 7 jecting fibres by producing laterally, closelyparallel lines of weakening upon opposite sides of the paper sheet andtearing the sheet along the lines, the tear extending from one line tothe other, and wetting the sheet only in the region in which it is to betorn before tearing is effected.

11. A method of manufacturing paper strips having thinned down irregularedges with projecting fibres by scoring them to produce laterally,closely spaced parallel lines of weakening upon opposite sides of thepaper sheet and tearing the sheet along the lines, the tear extendingfrom one line to the other.

12. A machine for the continuous production of paper strips havingthinned down irregular edges with projecting fibres, the said machinecomprising a supply device for 2. rolled sheet of paper and a pair ofcooperating rotatable cylinders, one having a circumferential groove andthe other a sharp edge entering the groove, the two cylinders being sodisposed as to weaken the sheet and then tear it into strips bystretching the sheet over the projection.

13. A machine for the continuous production of paper strips havingthinned down irregular edges with projecting fibres, the said machinecomprising a supply device for a rolled sheet of paper, means forproducing a line of weakening in the paper sheet and means for leadingoff the strips in laterally diverging directions to tear the sheet alongthe line of weakening.

14. A machine for the continuous production of paper strips havingthinned down irregular edges with projecting fibres, the said machinecomprising a supply device for a rolled sheet of paper, means forproducing a line of weakening in the paper sheet and means forstretching the sheet across the line of weakening to tear the sheet intostrips.

15. A machine for the continuous production of paper strips havingthinned down irregular edges formed of projecting fibres, the saidmachine comprising a supply device for a rolled sheet of paper, meansfor producing a line of weakening in the paper sheet and for tearing thesheet into strips, comprising means for gripping the sheet upon oppositsides of the line of weakening and for leading the strips off inlaterally divergent paths.

PERCY DUNSHEATH.

